Voltage stabilizer



June 7, 1949.

G. MAK

VOLTAGE STAB H I ZER Filed Jan. 10, 1948 FEG.

INVENTOR GERRIT MAK lizers.

Puhllhd June 1, 1949 VOLTAGE s'ranmznn Gerrit Mair, Heudon, South Australia, Australia, assignor to Hartford National Bank & Trust Company, Hartford, Conn., as trustee Application January 10, 1948, Serial No. 1,589

' In Australia September 11, 1945 Section 1, Public Law 690, August 8, 1948 Patent expires September 11, 1965 6 Claims. (Cl. 323-63) The present invention relates to voltage stabi- It is well known that voltages and currents may be stabilized by a bridge or the like device having incandescent lamps included in one or more of its arms. Ballast resistors in which the resistance varies with changes in the temperature of the resistor may also be usedfor the same purpose.

' before the device accommodates itself to the new conditions and stabilizes the. voltage. For this reason bridges and ballast resistors cannot be utilized to eliminate voltage or current variations which have a time period less than this v time interval.

It is the primary object of this invention to provide means for reducing rapidvariations in the output voltage from voltage stabilizing devices such as bridges, ballast resistors or the like.

According to the present invention a circuit having a sufficiently high Q factor to provide a substantial impedance to voltage variations which have a time period less than a predetermined 2 work are properly chosen, the network tends to maintain a substantially constant output voltage at the terminals 3 and 4-, irrespective ofvariations in the input voltage applied to the terminals l andi.

A stabilizer of the type shown in Figure 1 suffers from the defect that its action is not instantaneous as time is required for any increase or decrease in current flowing through the arm 5 to afl'ect the temperature of this arm so as to change its resistance. This defect is graphically shown in Figure 2 in which the graph (a) represents an input voltage which suddenly increases in value and the graph (b) represents the output value, is operatively associated with the voltage stabilizer.

In order that the invention may be more readily understood reference will now be made to the accompanying drawings in which:

Figure 1 is the circuit diagram of a well-known voltage stabilizer:

Figure 2 shows graphs illustrating variations in the input voltage and the resultant change in output voltage of the stabilizer of Figure 1:

Figure 3 is the circuit diagram of one embodiment of the invention:

Figure 4 is a graph illustrating the form of the output voltage ofthe stabilizer of Figure 3 when a variation occurs in the input voltage applied thereto: and V Figure 5 is the circuit diagram of an alternative form of the invention. 1

Referring to Figure 1, the arms 5, 6, l and8 form a bridge network having input terminals l and 2 and output terminals 3- and I. 'The'arm 5 of the bridge network includes a resistor of the type wherein variationsin the current flowin therethrough cause variations in temperature which, in turn, varies the resistance of the resister. A lamp filament constitutes a resistor of this type. The remaining arms 6, l and 8 are composed of resistors of normal type.

If the resistors constituting the bridge net-- voltage which also suddenly rises in value and then slowly decreases to its original value.

According to the invention a circuit such as a low pass filter or a circuit tuned to the frequency of the input voltage is interposed between the bridge network and the output terminals. This is shown in Figure 3 of the drawingswhere the reference numeral 9 indicates such a circuit. The circuit should have a relativelyhigh Q factor so'that' it presents a relatively high impedanc to rapid fluctuations in voltage.

Figure 4 graphically shows the nature of the output voltage from the circuit of the invention when the input voltage increases as shown in Fig- 'ure 2. The magnitudeof the fluctuation is reduced and the increase in voltage is more gradual. The higher-the Q factor of the circuit 9 the more effective is the stabilizing action.

A further embodiment of the invention is shown in Figure 5 wherein a very selective tuned valve amplifier is used instead of the circuit 9 of Figure 3. In Figure 5 the frequency selecting circuit comprises a. Wien, bridge formed by the resistors HI,- and I2 and the capacitors", I4 and J5. With this arrangement an output voltage'similar to that graphically shown in- Figure 4 is obtained, when the output voltage varies as illustrated in Figure 2.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1.A voltage stabilizing system comprising a netwbrk including a ballast resistance, input means to apply an alternating voltage of predetermined frequency to said network, the .amplitude of said alternating voltage being subject to fluctuations, output means to derive said alternating voltage from said network whereby said voltage is'stabilized by said ballast resistance for relatively slow fluctuations in amplitude, and an impedance circuit interposed between said network and said output means, said circuit having a characteristic presenting a relatively high impedance to amplitude fluctuations having a time period less than the time period of said predetermined frequency and a negligible impedance to voltage of the time period of said predetermined frequency.

2. A voltage stabilizing system comprising a network including a ballast resistance, input means to apply an alternating voltage of predetermined frequency to said network, the amplitude of said alternating voltage being subject to fluctuations, output means to derive said alternating voltage from said network whereby said voltage is stabilized by said ballast resistance for relatively slow fluctuations in amplitude, and a low pass filter interposed between said network and said output means, said filter having a band pass characteristic accommodating said predetermined frequency and discriminating against amplitude fluctuations having a time period less than the time period of said predetermined frequency.

3. A voltage stabilizing system comprising a network including a ballast resistance, input means to apply an alternating voltage of predetermined frequency to said network, the amplitude of said alternating voltage being subject to fluctuations, output means to derive said alternating voltage from said network whereby said voltage is stabilized by said ballast resistance for relatively slow fluctuations in amplitude, and a series resonant circuit interposed between said network and said output means and tuned to said predetermined frequency whereby said circuit presents a relatively high impedance to amplitude fluctuations having a time period less than that of said predetermined frequency and a negligible impedance to voltage of the time period of said predetermined frequency.

4. A voltage stabilizing system comprising a network including a ballast resistance, input means to apply an alternating voltage of predetermined frequency to said network, the amplitude of said alternating voltage being subject to fluctuations, output means to derive said alternating voltage from said network whereby said voltage is stabilized by said ballast resistance for relatively slow fluctuations in amplitude, and a selective electron discharge tube amplifier inter- 4 posed between said network and said output means and tuned to said predetermined frequency whereby amplitude fluctuations having a time period less than that of said predetermined frequency are attenuated by said amplifier.

5. A voltage stabilizing system comprising a four arm resistance bridge one arm of which is constituted by a ballast resistance, input means to apply an alternating voltage of predetermined frequency across one pair of opposing diagonals in said bridge, said alternating voltage being subject to amplitude fluctuations, output means to derive said alternating voltage from the other pair of opposing diagonals to said bridge whereby said voltage is stabilized for relatively slow fluctuations in amplitude, and an impedance circuit interposed between said bridge and said output means, said circuit presenting a relatively high impedance to amplitude fluctuations of voltage having a time period less than the time period of said predetermined frequency and a negligible impedance to voltage of the time period of said predetermined frequency.

6. A voltage stabilizing system comprising a four arm resistance bridge one arm of which is constituted by a ballast resistance, input means to apply an alternating voltage of predetermined frequency across one pair of opposing diagonals in said bridge, said alternating voltage being subject to amplitude fluctuations, output means to derive said alternating voltage from the other pair of opposing diagonals to said bridge whereby said voltage is stabilized for relatively slow fluctuations in amplitude, and a selective electron discharge tube amplifler interposed between said network and said output means and tuned to said predetermined frequency whereby amplitude fluctuations having a time period less than that of said predetermined frequency are attenuated by said amplifier.

GERRIT MAK.

REFERENCES CITED UNITED STATES PATENTS Name Date Crouse Nov. 13, 1928 Number 

